https://gcc.gnu.org/bugzilla/show_bug.cgi?id=105295
Bug ID: 105295
Summary: missed optimization with -ftrapv for conditional
constants
Product: gcc
Version: 12.0
URL: https://godbolt.org/z/4rojo77a7
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: tree-optimization
Assignee: unassigned at gcc dot gnu.org
Reporter: roland.illig at gmx dot de
Target Milestone: ---
~~~c
int sum_const(_Bool a, _Bool b)
{
return (a ? 1 : 0 ) + (b ? 1 : 0);
}
int sum_unknown(int a, int b)
{
return a + b;
}
~~~
For both functions, GCC calls __addvsi3, even though in sum_const, it is easy
to see that no overflow can ever happen since the sum is always in the range [0
... 2].
Clang optimizes this code reasonably.
ICC apparently does not care about -ftrapv at all.
